title: Remediation of soil co-contaminated with petroleum and heavy metals by the integration of electrokinetics and biostimulation.
abstract: Successful remediation of soil co-contaminated with high levels of organics and heavy metals is a challenging task, because that metal pollutants in soil can partially or completely suppress normal heterotrophic microbial activity and thus hamper biodegradation of organics. In this study, the benefits of integrating electrokinetic (EK) remediation with biodegradation for decontaminating soil co-contaminated with crude oil and Pb were evaluated in laboratory-scale experiments lasting for 30 days. The treated soil contained 12,500 mg/kg of total petroleum hydrocarbons (TPH) and 450 mg/kg Pb. The amendments of EDTA and Tween 80, together with a regular refreshing of electrolyte showed the best performance to remediate this contaminated soil. An important function of EDTA-enhanced EK treatment was to eliminate heavy metal toxicity from the soil, thus activating microbial degradation of oil. Although Tween 80 reduced current, it could serve as a second substrate for enhancing microbial growth and biodegradation. It was found that oil biodegradation degree and microbial numbers increased toward the anode and cathode. Microbial metabolism was found to be beneficial to metal release from the soil matrix. Under the optimum conditions, the soil Pb and TPH removal percentages after 30 days of running reached 81.7% and 88.3%, respectively. After treatment, both the residual soil Pb and TPH concentrations met the requirement of the Chinese soil environmental quality standards.
authors.affiliation: State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China. bluemanner@163.com
authors.forename: Zhi-Yong
authors.initials: ZY
authors.lastname: Dong
authors.forename: Wen-Hui
authors.initials: WH
authors.lastname: Huang
authors.forename: Ding-Feng
authors.initials: DF
authors.lastname: Xing
authors.forename: Hong-Feng
authors.initials: HF
authors.lastname: Zhang
mesh_terms: D001673:Biodegradation, Environmental; D002614:Chelating Agents / Q000737:chemistry; D004492:Edetic Acid / Q000737:chemistry; D004563:Electrochemistry; D004566:Electrodes; D052918:Environmental Restoration and Remediation; D004867:Equipment Design; D006838:Hydrocarbons / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007854:Lead / Q000302:isolation & purification*; D059013:Microbial Consortia; D009995:Osmosis; D010578:Petroleum / Q000378:metabolism*; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis*; D013997:Time Factors; D018675:Toxicity Tests
chemical_list: D002614:Chelating Agents; D006838:Hydrocarbons; D010578:Petroleum; D012989:Soil Pollutants; D007854:Lead; D004492:Edetic Acid
keywords: Bioelectrokinetic; Chelating agent; Ecotoxicity; Hydrocarbons; Lead